Jackson's eldest son, Prince, now 19, also shared a loving tribute online.
"Happy birthday to the Man who was more than a legend. I love you," he captioned an Instagram post of a poem – "The Myth, The Legend, The Man" – he wrote about his father, which reads:
"To many he is king, to me, a man
All he inspires, to lead a noble cause.
Everyone is family, not a fan
Even while receiving thunderous applause.
The many know the Legend and the Myth,
A lucky few know the Man as he is
But not as the Jackson family fifth.
'Son, Brother, Father,' these few know him as.
He is the Myth, the Legend and the Man.
He cares for his mother and his children,
The world and everyone, he is a lamb.
He is pure, tested, yet has forgiven.
He is the archangel known as Michael
He is with us and our tears we must stifle."
Jackson's daughter Paris, 18, later shared her older brother's poem on social media, writing on Instagram, "proud of you big brother. and happy birthday to the man that means more to us than anything and anyone ever could."
The pop star's older sister, La Toya, 60, also added her voice to the "Happy Birthday" choir, tweeting, "Happy birthday to the most #loving #kindhearted #talented #brother in the #world! Love U."